The present invention concerns the therapeutic use of phosphoryl-L-serine-N-acyl-sphingosine composed of a mixture of compounds of formula I or II, ##STR1## in which n is an integer of 6-16 and R means an acyl residue of a higher aliphatic acid having between 16 and 24 carbon atoms, the distribution of the values for n and R being those of a natural spingomyelin. The invention also includes a new process for the preparation of these compounds, as well as pharmaceutical preparations containing said compounds as active ingredients. The ratio of the mixture of compounds of formulas (I) and (II) is not critical in order to use the compound of the present invention. The compound, as previously defined, was prepared by treatment with phospholipase D, as described in Biochemistry vol. 28, No. 8, 1989, 34-57, starting from a derivative of spingomyelin (i.e. phosphorylcholine-N-acyl-sphingosine, in which the acyl group was derived from higher aliphatic acids of different molecular size and was variable between C12 and C24), and particularly to an analog of a spingomyelin having an acyl group derived from 4-doxyl-pentanoic acid on the sphingosine amino group instead of the acyl residue R. In the cited paper there are no indications about pharmacological properties of the derivatives.